Hi @aditi.agarwal, if you are using the Apache Airflow Multi-Tier solution, you can restrict all the outbound traffic. In principle, Airflow can run without the need of doing external requests.
Note that if you restrict all the outbound traffic, you won't be able to use the
Public DAG repository UI input.
Also please advise if its possible to select the VNET and address space during the creation of the the Airflow Multi-tier solution
About your second question, it is not possible to do so. The solution creates a VNET with a predefined address space that is not customizable via UI inputs when launching the solution.